Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

Biochar in growing media: a sustainability and feasibility assessment - SP1213

Description
Peat land in the UK has a high environmental and ecological value. However, peat has long been valued as a medium in which to propagate plants or to to grow them outside of soil, both for production of vegetables and in gardening.
This has led to an industry that is based around manufacture of “growing media” that has depended on the unsustainable exploitation of peatland. The use of growing media is increasing, especially in the amateur gardener market.
There is now widespread agreement in the growing media and horticultural industries and the use of peat is unsustainable and with a renewed effort to accelerate the adoption of peat alternatives in growing media (which are often a mix of ingredients) there is an interest in the use of materials not previously considered. However, the characteristics of growing media are specific – even to the particular plant that is being grown – and cost of alternatives is an issue.
Biochar has not been widely considered in the context within the industry, although there has been much activity at a research level as to how it may contribute to storage of carbon as well as increased fertility of soils to which it is added. Biochar is a form of charcoal, but does not have to be made from wood and produced under a very controlled process to as to exhibit precise and most useful properties.
In this project we will be consulting companies that manufacture growing media to gauge their thoughts about its suitability (we have a range of different types we can show that differ in their all-important physical properties). We will also discuss this with business and people who use or retail growing media.
Using our findings we will make estimates of how expensive biochar will be as an ingredient of a growing media mixes for different purposes. Then, importantly, we will consider where biochar might be made, the technology used to make it, and what it is made from. This will establish a measure of how sustainable biochar may be relative to peat in these products, and whether it is worthy or more investigation and experimentation for in this context.
Objective
We seek to understand if biochar can be important in achieving zero use of peat in horticultural growing media.
Our approach will be to first establish the feasibility and potential scale of the use of biochar in peat replacement for UK horticultural growing media (Workpackage 1). We will then – on the basis of the quantity of biochar or biochar types required – assess the sustainability of its provision (Workpackage 2). Both Workpackages comment on impacts and opportunities for industries connected to horticultural growing media.
Although carbon balance is recognised as part of the wider reason for considering use of biochar in horticulture and agriculture, the implications for greenhouse gas emissions are not an explicit component of this project. The format of project outputs, however, will lend themselves to life-cycle analysis at a later date.
Workpackage 1 – Feasibility Assessment
Feasibility concerns acceptability of biochar as a minor or major constituent of growing media for different segments of the market. Perceptions of manufacturers, retailers and end-users in terms of visual appeal, physical form and functional properties are essential. Feasibility encompasses questions about price, technology and certainty of supply. These will be addressed using a tiered approach beginning with Key Informants, expert review and structured consultation with a stakeholder group. First we create materials to engage these groups.
Objective 1.1 Preparation of briefing document on biochar in growing media – mid-February (3 days)
Carbon Consulting and Carbon Gold
We will prepare a briefing document that summarises the drivers, opportunity and challenges in consideration of biochar as a replacement constituent to peat-containing growing media from the perspective of producers, retailers and end-users. This document will be designed to engage those interviewed later and will be reviewed by both the ADAS and University of Edinburgh team before use.
Objective 1.2 Establish an inventory of Key Informants – mid-February (1 day)
Carbon Consulting, Carbon Gold, ADAS and University of Edinburgh
We will develop a schema to categorise stakeholders, distinguishing sub-categories to distinguish (for example) manufacturers with and without existing peat-free products, small retailers from large, propagators of different commercial plants. The GMA and HTA will be consulted as relevant trade associations. Alternative names will be put to each sub-category as potential interviewees.
Objective 1.3 Select biochar samples for use in Key Informant meetings – mid-February (0.5 days)
University of Edinburgh
Using the UK Biochar Research Centre (University of Edinburgh) database we will select a strategic set of pre-characterised biochar samples from the linked Charchive. These will reflect a range of visual appearance and physical properties potentially available from commercial producers to manufacturers of growing media.
Objective 1.4 Document perceptions of Key Informants – early March (7 days)
ADAS, Carbon Consulting
The briefing paper and biochar samples will be used to facilitate face to face discussions with members or representatives of each category identified by the schema established in Objective 1.2. Informant perceptions, questions and views on the practicality, utility and acceptability of biochar in growing media will be elicited, together with a discussion of price. Biochar samples will be ranked according to their perceived utility.
Objective 1.5 Collate and assess information on feasibility – e/o March (3 days)
University of Edinburgh
We will consider the possible costs for biochar created from the feedstock types preferred by Key Informants (Objective 1.3), assuming the quantity required to satisfy its feasible content in growing media. Using the approaches we established in SP576 we will review the economic, logistical and regulatory feasibility of using of biochar in growing media in different market segments, taking into account feedstock supply within the UK and overseas and the possibility of biochar import.
Workpackage 2 – Sustainability Assessment
This will consider any requirement for the use of primary rather than secondary resources and associated implications for biodiversity, pollution associated with biochar production technologies (pyrolysis), transportation requirements and ‘end of life’. The environmental implications of using biochar will be compared to those of peat.
Objective 2.1 Sustainability and appraisal for biochar in growing media – late April (3 days)
University of Edinburgh
Based on the rankings of biochar types obtained in Objective 1.4 the environmental sustainability of biochar production for the manufacture, use and disposal of horticultural growing media (amateur and professional). Sustainability assessment will be made on the same materials according to the criteria announced by the Task Force in January 2012 assuming current usage of media and feasible biochar content.
Objective 2.2 Expert review of integrated findings – late April (1 day)
Expert panel
Through a facilitated webinar and PowerPoint presentation an international panel of experts (engaged in biochar research or the horticultural industry) will review preliminary findings such that they may be tested and revised.
Objective 2.3 Stakeholder consultation using reviewed output – early-May (4 days)
Knowledge Transfer Network
The opinions of up to 25 national and international stakeholders will be recorded through telephone interviews. This will include a consultation of businesses currently involved in marketing biochar products as well as those not previously aware of biochar but potential users of biochar containing growing media.
Objective 2.4 Final report – e/o May (4 days)
University of Edinburgh
A draft report will be updated to reflect stakeholder feedback in Objective 2.3 and comments form the Defra Project Officer. The Final Project Report will be submitted at the end of May 2012.
Project Documents
• FRP - Final Report : SP1213 Final Report   (834k)
Time-Scale and Cost
From: 2012

To: 2012

Cost: £19,953
Contractor / Funded Organisations
University of Edinburgh
Keywords
Soil